Saturated-steam generator



United States Patent [72] Inventor Jurgen Vollradt [51] Int. Cl. F22b 1/16 Frankfurt am Main-Niederrad, Germany [50] Field of Search 122/3 1; [21] App1.No. 631,737 261/113, 114,124,125 [22] Filed April 18, 1967 1 [45] Patented Dee. 8,1970 References C1tedl 1 [73] Assignee Licentia Patent Verwaltungs G.m.b.ll. UNITED STATES PATENTS Theodnr-Stern-Kai, Frankfurt am Main, 2,256,438 9/1941 Larsen 261/114 Germany 2,344,077 3/ 1944 Bredtschneider 122/31 g 9' FOREIGN PATENTS ermany [31] No. L53 ,389 739,469 10/ 1943 Germany 122/31 Primary Examiner-Charles J. Myhre Attorney-Spencer & Kaye [54] SATUliATEDiTE?MgENERAT0R ABSTRACT: A saturated steam generator of the Loeffler type 13 ch raw having a plurality of water levels disposed in a vessel, with [52] US. Cl. 122/31, each water level being provided with a separate superheated 261/ 1 l3, 261/1 14, 261/ 124 steam delivery system and a separate water inlet.

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BY 4 V I WI, 507;

1 SATURATED-STEAM GENERATOR BACKGROUND or THE INVENTION The present invention relates to a saturated steam generator, and particularly to a generator of the Loeffler boiler-type for use with steam-cooled nuclear reactors.

Prior art attempts to generate the large quantities of saturated steamrequired by steam-cooled nuclear reactors have generally centered on three systems: heat exchangers; Loefl'ler boilers; and injection cooling systems.

For generating the large amounts of saturated steam required for nuclear reactors, the conventional heat exchanrated steam is generated by applying the heat from asuper heater directly to the water to vaporized. Since it is only known to provide but a single water level in such boilers, the

ratio of the .water surface area to its volume is very low,.especially under high pressure, sothat they can only produce the large amountsofhigh-pressure saturated steam required'by nuclear reactors if theyare given undesirably large overall dimensions and great wall thicknesses. The only alternative would be to replace the single boiler with an uneconomically large number of individual structural units.

In injection cooling systems, water is injectedinto super heated steam so as to produce saturated stearn. However, such systems are generally used only to regulate steam temperatures andnot primarily for generating saturated steam. Their principal drawback for use with nuclear reactors is the fact that they have a low water storagevolume which renders the regulation of the entire installation relatively difficult. Moreover, since they have a poor ability to transfer heat from the superheated steam to the water droplets whoseternperature is near the boiling point, the resulting steam will be relatively wet unless the cooling systems are given undesirably large dimensions or fillers are used. However, fillers tend to become soiled and this can cause considerable difficulty, par- It is a primary object of the present invention to eliminate these drawbacks and difficulties.

another object of the present invention is to generate large FIG. 6 is a cross-sectional detail view of a modified form of construction of the arrangement of FIG. 5.

FIG. 7 is a cross-sectional detail view taken along the line 7-7 ofFIG. 6. FIG. 8 is a view similar to that of FIG. 2 showing one feature of the present invention. FIG. 9 is a simplified perspective view of a portion of various embodiments of the present invention.

quantities of high-pressure saturated steam in an efficient manner.

Yet 11 another object of the present invention is to achieve BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified, longitudinal, cross-sectional view of a Loeffler type boiler according to the present invention.

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1.

FIG. 3 is a view similar to that of FIG. 2 of another embodiment of the present invention.

FIG. 10 is a view similar to that of FIG. 9 of a modified form of construction of the portion illustrated in FIG. 9.

FIG. 11 is a view similar to that of FIG. 9 showing other features of the present invention.

FIG. l2 is a simplified, axial, cross-sectional, detail view of a further embodiment of the present invention.

FIG. 13 is a cross-sectional view takenalong the line 13-13 of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1 and 2, there is shown a Loefflertype boiler, provided, according to the present invention, with a plurality of water levels. Disposed within thecontaining vessel l is a lateral wall 2 provided with inlet openings 3 for the passage of superheated steam introduced through the inlet pipe 4 into a superheated steam distributor region 5. Steam passing through the openings 3 enters delivery tubes 6 mounted on the wall 2. Also mounted on the wall 2 are a plurality of longitudinally extending troughs 7 each of which is provided to hold water at one of the water levels 11 in the vessel l. The bottom of the vessel 1 itself constitutes the container for the lowermost water level. e

The water W to be heated flows into the troughs? and the bottom of the vessel 1 via respective supply tubes 8. The tubes 6 for delivering superheated steam to the various water levels are arranged in a plurality of layers, as is best shown in FIG. 2, each layer corresponding to a respective water level. Superheated steam flowing through the tubes 6 is discharged into each water body via openings 9 for transforming the water in each trough 7 and at the bottom of vessel 1 into saturated steam S which is discharged through the outlet pipe 10 at the top of vessel 1. The vessel 1 isprovided witha space 12 for the passage of saturated steam S from the water levels 11 to the pipell).

FIG. 3 shows another form of construction according to the present invention in which a plurality of saturated steam discharge pipes l3, I4, 15, and 16 are provided inthe cylindrical wall of vessel 1. Pipe 16 is provided for the passage of saturated steam from the uppermost water level, pipes'13 are pro- 'vided for removing saturated steam from the next succeeding water level, pipes are provided for the third water level from the top, and pipes 15 are provided for the lowermost water level maintained at the bottom of the vessel 1.

, .By providing separate discharge pipes for each water level, it is possible to reduce the lateral dimensions of the space 12 between the side walls of the troughs and the side of the vessel 1 by increasing the surface area of each water level, thus increasing the rate at which water can be converted into saturated steam within the vessel. I

In the embodiments of FIG. 1 and 3, as well as in the embodiments to be described in detail below, it is desirable that the saturated steam discharge pipes be disposed as high as possible above their associated water levels in order to give the saturated steam a maximum opportunity to dry out before FIG. 4 is a viewsimilar to that of FIG. 2 of still another embodiment of the present invention.

FIG. 5 is a view similarto that of FIG. 2 of yet another embodiment of the present invention.

levels, a plurality of pipes 13' are provided for the discharge of saturated steam from the two intermediate water levels 17 and .18, and a plurality of pipes 15' are provided for the discharge of saturated steam from the lowest two water levels.

In the embodiment shown in FIG. 5, two troughs are provided at each but the lowest level in the vessel, and above each water level are provided a plurality of inclined sheets 19 defining guide channels 20 for the passage of saturated steam from the water levels to the discharge pipes. Each of the sheets 19 is longitudinally coextensive with its respective trough. the provision of the guide channels 20 assures that the saturated steam will have the longest possible upward flow path to the discharge pipes and assures that the steam flowing to the discharge pipes will not have an undesirably high water content. The sheets 20 can be mounted on the transverse wall 2 (FIG. 1) and may additionally be supported by the end wall of vessel 1 through which the' water inlet pipes 8 extend.

FIG. 6 shows an arrangement in which one side wall of the trough 7 is constituted by a portion of the wall of vessel 1 and in which a plurality of corrugated, or otherwise suitably shaped, metal sheets 21 are disposed in the steam guide channels between, above and below the sheets 19 for the purpose of drying the saturated steam.

As is shown in FIG. 7, there are sheets 21 provided in the longitudinal direction of the vessel 1 to permit the water which condenses out of the steam to drain olT into longitudinally extending drains 21a. From the drains, the condensed water flows back to its water level via tubes 22. The sheets 21, as well as the drains 21a and tubes 22 can be supported by the sheets 19. The sheets 21 above the highest sheet 19 can be additionally or alternatively supported by the bottom of the next higher trough 7 FIG. 8' shows a modified form of construction of the embodiment of FIG. 1 and 2 in which a plurality of overflow pipes 23 are provided, each overflow pipe extending between an adjacent pair of water levels. These overflow pipes permit excess water at one level to flow off to the next lower water level. As a result, overflowing water is prevented from wetting the saturated steam. Moreover, the provision of these pipes 23 eliminates the need for regulating the flow of water to all but the lowermost water level in the vessel 1, even if all of the water levels above the lowermost one are overflowing at the same time.

Referring now to FIG. 9, there is shown one form of superheated steam delivery arrangement according to the presentinvention which is constituted by a plurality of tubes 6 associated with each trough 7, each tube being provided with superheated steam outlet openings 9 distributed around only the lower half of its circumference. This location for the outlet openings 9 serves to increase the time during which the superheated steam remains in the water of trough 7 so as to increase the efficiency of the heat transfer between the superheated steam and the water.

FIG. shows another form of construction for the superheated steam delivery system according to the present invention in which each trough 7 and the bottom of vessel 1 is provided with a perforated partition floor 25 cooperating with floor 24, or the vessel bottom, to define a double floor. In the illustration of FIG. 10, the floor 25 is spaced above the floor 24 of trough 7 and is perforated with a plurality of steam outlet openings 9. Superheated steam is introduced between floors 24 and 25, while the water to be converted into steam is maintained above floor 25; Superheated steam passing through openings 9 rises through the water above floor 25 and converts this water into steam. The superheated steam below floor 25 is preferably maintained at a sufficient pressure to prevent any substantial amounts of water from passing through the openings 9 into the steam delivery space.

FIG. 11 shows another variation according to the present invention wherein a trough 7 having a superheated steam delivery system of the type shown in FIG. 10 is provided with a plurality of flat, vertically spaced and horizontally offset steam baffle strips 27 or curved bafiles 27 disposed below the water level in trough 7 so as to cause the superheated steam flowing from openings 9' to follow a longer flow path through the water W. This longer flow path permits a more efficient transfer of heat from the steam to the water. As a result, the

depth H, of each water body can be reduced, thus permittin a more compact structure to be realized. The baffles 27 or can be mounted between the longitudinal end walls of the trough 7.

FIG. 12 and 13 show a modified form construction of the arrangement shown in FIG. 10 wherein the trough 7 is provided with a bottom wall 24' formed with a plurality of downwardly extending hollow fins 26. These fins extend into the region through which saturated steam flows from the next lower water level to its associated steam outlet pipes. Superheated steam below floor 25 circulates inside the fins 26 and heats them to a high temperature so that they will act to dry the saturated steam passing between them. The floor of each trough may be provided with such fins for drying the saturated steam produced at the next lower water level.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

IClaim:

1. In a Loeffler-type boiler for producing saturated steam, the improvement comprising containers disposed in said boiler for holding water at a plurality of vertically spaced levels within said boiler, said containers including at least one trough at each water level for holding a body of water, and a separate water inlet for each said trough.

2. An arrangement as defined in claim 1 wherein said boiler is connected for delivering saturated steam to a steam-cooled nuclear reactor.

3. An arrangement as defined in claim 1 wherein the bottom of said boiler also constitutes a container for holding water which defines the lowest water level in said boiler.

4. An arrangement as defined in in claim 1 wherein at least two separate troughs are provided at the same level within said boiler.

5. An arrangement as defined in claim 1 wherein said boiler is provided with a pluralityof steam discharge pipes at least a respective one of which is disposed above each water level.

6. An arrangement as defined in claim 1 wherein said boiler is provided with a plurality of steam discharge pipes each disposed for conveying steam produced at at least two respective adjacent water levels.

7. An arrangement as defined in claim I further comprising a plurality of steam baffles disposed in at least on one-of said troughs in the region thereof which is to be filled 'with water.

8. An arrangement as defined in claim 1 wherein each of said troughs is provided with adouble floor through which superheated steam flows, the upper side of each said double floor being provided with steam outlet passages.

9. An arrangement as defined in claim 8 wherein the bottom of each said double floor defines a plurality of downwardly extending hollow fins in which superheated steam circulates for drying the steam emanating from the next lower water level.

10. An arrangement as defined in claim 1 further comprising at least one water overflow pipe extending between two adjacent water levels for conveying overflow water from the upper one of said water levels to the lower one thereof.

11. An arrangement as defined in claim 1 further comprising a plurality of superheated steam supply tube, at least one for each water level, each positioned to be immersed in the water at its associated level and having a plurality of steam passages distributed only around the lower half of its circumference. Cm 12. In a Loeffler-type boiler for producing saturated steam, the improvement comprising: containers disposed in said boiler for holding water at a plurality of vertically spaced levels within said boiler; and means defining steam guide channels disposed above at least the uppermost one of said levels for guiding steam produced in said boiler to steam discharge pipes provided in the wall of said boiler. Cm 13. An arrangement as defined in claim 12 further comprising metal sheets disposed in said guide channels for drying the steam passing therethrough. 

